Method and apparatus for reducing phase imbalance in radio frequency signals

Abstract

Systems and method for reducing phase imbalance in radio frequency (RF) signals are disclosed. The phase imbalance in an RF signal may be due to phase imbalance in the local oscillator used for upconversion in a transmitter, and downconversion in a receiver. The RF signal is converted to a digital signal. The phase imbalance in the digital signal is measured by using a digital signal processor. The digital signal processor generates a compensation signal in response to the measurement of the phase imbalance. The compensation signal is used to generate a tuning signal to tune the local oscillator used for the upconversion or downconversion, thereby reducing the phase imbalance.

Description

FIELD OF THE INVENTION [0001] This invention generally relates to the field of communication systems, and more specifically to communication systems for reducing phase imbalance in radio frequency (RF) signals. BACKGROUND OF THE INVENTION [0002] Radio communication systems are used to transmit and receive information over long distances. The fundamental blocks of radio communication systems include a Frequency Generation Unit (FGU), a transmitter, communication channels, and a receiver. A transmitter transmits a radio frequency (RF) signal, which is obtained by modulating a baseband signal. The baseband signal is modulated by using a carrier signal. In some cases, the baseband signal is not modulated directly. Instead, the baseband signal is modulated by using an intermediate frequency (IF) signal, and then up converted to the RF signal for transmission. In any case, the FGU generates the required carrier signal, whether IF or otherwise, so that the baseband signal may be modulated ...

AI Technical Summary

Problems solved by technology

However, developing direct conversion LOs for use in multi-band (multiple frequency) radio communication systems (which is a current requirement) involves complex design techniques.

One of the problems of satisfying these requirements is that a direct conversion LO design that meets these requirements may introduce a phase imbalance in LO signal generation.

As a result, the direct conversion LO may introduce or increase the phase imbalance in the RF signal during up-mixing or increase the phase imbalance in the baseband signal during down-mixing.

The DLL scheme is not advantageous because it introduces additional hardware that adds additional cost and space to the transceiver design.

Currently known quadrature phase balancing schemes do not correct the phase imbalance so that the quadrature error targets are as small as possible and acceptable for certain applications.

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